Major Variation in Charge rates at Supercharger Station

I charge frequently at the San Juan Capistrano, CA Supercharger and I have noticed something that is starting to become a small problem for those who supercharge often, over there at least.

I have been at the supercharger with no other cars charging and I plug in and after 5 minutes the max charge rate I am receiving is about 150 mi/hr. I unplug and move two outlets over and it goes up to 280mi/hr.

Now, when I go there, I plug in and wait to see if I have a "good" charger. If not, I switch, sometimes 2 to 3 times to find a faster charger.

I do the best I can to see if it is because another car is charging on the same "circuit" but I cannot correlate that as the cause and I've spent some time thinking about it, and talking to others charging experiencing the same situation.

The outside temp is around 70 degrees and the SOC of my car car is not relevant since I can move a cable over and see 2x the charge rate. I have an A pack battery.

The "problem" is that over an hour of waiting the difference in my car's charge lever is pretty significant if I have a "slow" charger.

just had something similar in Hawthorne. Tried two different ones and only got 58 kW. No other cars there. Moderate temperatures, moderate driving before. Do you see this at other Superchargers?

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Based on what I've read the superchargers have a stack of power modules inside that can be turned on/off or switched to the B plug depending on need. Possibly some of the modules have gone bad in a particular charger? Would be good to know and if this is something that should be reported. (I'm all talk, don't even own a Tesla - yet.)

I also do not yet own a tesla, but I'm wondering if the charge rate is usually just-under a multiple of 10kw -- if so, it sounds like Kbsilver's theory might be right, and some chargers in the cabinet have failed?

I noticed the issue on 1A at SJC before. The charge rate would be all over the place. 250 amps, then 100, then 10 then 150, then 200 back and forth. I called support and they said they would notify the supercharger team as it looked like there was something wrong with that one.

I actually experienced this for the first time today at the Tesla Fremont supercharger. When I first plugged in, I maxed out at 67miles per hour charge pulling around 130amps. I moved to a second charger, got up to 198mi/hr at 155a but not getting anywhere close to what I used to get. I have a picture of it charging at 358mi/hr at 294a in the past.

I noticed the issue on 1A at SJC before. The charge rate would be all over the place. 250 amps, then 100, then 10 then 150, then 200 back and forth. I called support and they said they would notify the supercharger team as it looked like there was something wrong with that one.

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I saw the same thing, also on 1A at SJC. It was late at night and nobody else was there. I recall it was something ludicrously slow like 9 kW, but I don't remember for sure. Moved over to 2A and it went up to around 90 kW or so.

I was at another Supercharger yesterday and the same thing happened. I spoke to another MS owner who was a few stalls over(supercharger, not restroom) and he showed me that he was charging at 290mi/hr. and I was charging at 150 mi/hr. We were both under 50% SOC. His VIN was about the same as mine. Both have original battery packs.

I want others to chime in on this, if you wish:

Do you think Tesla is "governing" in any way the juice going to us for a charge?

I cannot find any rhyme or reason for the variation.

It is a pain because I know that when supercharging I will need to "shop" for the best plug. Additionally sometimes the "good" plug will drop power substantially during the charge as well.

It would be nice to have Tesla tell us what's going on here. I was never told when I bought my car, that when supercharging sometimes it will take twice as long to get the same charge as other times for no apparent reason. If promised or sold on a rate of charge, it would be nice to see that reliably. Do you think I am being unreasonable?

I was at another Supercharger yesterday and the same thing happened. I spoke to another MS owner who was a few stalls over(supercharger, not restroom) and he showed me that he was charging at 290mi/hr. and I was charging at 150 mi/hr. We were both under 50% SOC. His VIN was about the same as mine. Both have original battery packs.

I want others to chime in on this, if you wish:

Do you think Tesla is "governing" in any way the juice going to us for a charge?

I cannot find any rhyme or reason for the variation.

It is a pain because I know that when supercharging I will need to "shop" for the best plug. Additionally sometimes the "good" plug will drop power substantially during the charge as well.

It would be nice to have Tesla tell us what's going on here. I was never told when I bought my car, that when supercharging sometimes it will take twice as long to get the same charge as other times for no apparent reason. If promised or sold on a rate of charge, it would be nice to see that reliably. Do you think I am being unreasonable?

John

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Yes, actually I do. Glitches happen. First, did you make sure you weren't at a paired stall? Many sites have paired stalls that aren't adjacent to each other. If they weren't paired stalls, report it to Tesla and it will be fixed.

I was at another Supercharger yesterday and the same thing happened. I spoke to another MS owner who was a few stalls over(supercharger, not restroom) and he showed me that he was charging at 290mi/hr. and I was charging at 150 mi/hr

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Please don't report supercharging speeds in MPH - the MPH value on the screen is extremely misleading. Much more useful to report in kW - either by setting your screen to display in kW, or by multiplying the numbers shown for volts and amps which are always accurate.

There certainly are variations in the charge rate due to charger sharing, faulty chargers, temperature and probably other factors - but it's hard to analyse based on MPH reports.

The reason the MPH figure is unhelpful is that it is an average over the whole charging session. So on a supercharger it reads much lower than reality for the first few minutes (the charge gradually ramps up to full speed, so during this phase the MPH is showing about half the true value and gradually corrects itself), but conversely at the end of the charge the true charging rate tapers off to a very low value and the displayed MPH is much higher than the true rate since it is still counting the fast charging that occurred near the beginning.

I was at another Supercharger yesterday and the same thing happened. I spoke to another MS owner who was a few stalls over(supercharger, not restroom) and he showed me that he was charging at 290mi/hr. and I was charging at 150 mi/hr. We were both under 50% SOC. His VIN was about the same as mine. Both have original battery packs.

I want others to chime in on this, if you wish:

Do you think Tesla is "governing" in any way the juice going to us for a charge?

I cannot find any rhyme or reason for the variation.

It is a pain because I know that when supercharging I will need to "shop" for the best plug. Additionally sometimes the "good" plug will drop power substantially during the charge as well.

It would be nice to have Tesla tell us what's going on here. I was never told when I bought my car, that when supercharging sometimes it will take twice as long to get the same charge as other times for no apparent reason. If promised or sold on a rate of charge, it would be nice to see that reliably. Do you think I am being unreasonable?

John

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Johnmodels,
What arg said is totally true about the MPH reporting. It is an average achieved over the amount of time you have been charging. It varies greatly. Could this be the possible reason you are getting such deviant rates?

In some instances, these variations could be due to conditions in the car itself and often change after a few minutes of charging. I've seen this effect with my car. The supercharger varies its output based on realtime data coming from the vehicle. This effect is quite obvious when driving in hot or cold weather, but it may be subject to other factors too. It seems unlikely that there would be dozens of supercharger locations with defective hardware.